Just do the method call directly in Module#delegate, if we can (we cannot for method names ending in '='). Two reasons: 1) it's faster, see https://gist.github.com/1089783 and 2) more importantly, delegate should not allow you to accidentally call private or protected methods.

activesupport/CHANGELOG

@@ -1,11 +1,13 @@
 *Rails 3.2.0 (unreleased)*
 
+* Removed support for using Module#delegate to delegate to non-public methods [Jon Leighton]
+
 * The definition of blank string for Ruby 1.9 has been extended to Unicode whitespace.
 Also, in 1.8 the ideographic space U+3000 is considered to be whitespace. [Akira Matsuda, Damien Mathieu]
 
 * The inflector understands acronyms. [dlee]
 
-* Deprecated ActiveSupport::Memoizable in favor of Ruby memoization pattern [José Valim] 
+* Deprecated ActiveSupport::Memoizable in favor of Ruby memoization pattern [José Valim]
 
 * Added Time#all_day/week/quarter/year as a way of generating ranges (example: Event.where(created_at: Time.now.all_week)) [DHH]
 

activesupport/lib/active_support/core_ext/module/delegation.rb

@@ -123,6 +123,9 @@ class Module
     line = line.to_i
 
     methods.each do |method|
+      method = method.to_s
+      call   = (method[-1..-1] == '=') ? "public_send(:#{method}, " : "#{method}("
+
       on_nil =
         if allow_nil
           'return'
@@ -132,7 +135,7 @@ class Module
 
       module_eval(<<-EOS, file, line - 5)
         def #{method_prefix}#{method}(*args, &block)        # def customer_name(*args, &block)
-          #{to}.__send__(#{method.inspect}, *args, &block)  #   client.__send__(:name, *args, &block)
+          #{to}.#{call}*args, &block)                       #   client.name(*args, &block)
         rescue NoMethodError                                # rescue NoMethodError
           if #{to}.nil?                                     #   if client.nil?
             #{on_nil}                                       #     return # depends on :allow_nil

activesupport/test/core_ext/module_test.rb

@@ -26,10 +26,20 @@ module Yz
   end
 end
 
-Somewhere = Struct.new(:street, :city)
+Somewhere = Struct.new(:street, :city) do
+  protected
+
+  def protected_method
+  end
+
+  private
+
+  def private_method
+  end
+end
 
 Someone   = Struct.new(:name, :place) do
-  delegate :street, :city, :to_f, :to => :place
+  delegate :street, :city, :to_f, :protected_method, :private_method, :to => :place
   delegate :upcase, :to => "place.city"
 end
 
@@ -69,6 +79,14 @@ class ModuleTest < Test::Unit::TestCase
     assert_equal "Chicago", @david.city
   end
 
+  def test_delegation_to_protected_method
+    assert_raise(NoMethodError) { @david.protected_method }
+  end
+
+  def test_delegation_to_private_method
+    assert_raise(NoMethodError) { @david.private_method }
+  end
+
   def test_delegation_down_hierarchy
     assert_equal "CHICAGO", @david.upcase
   end